Wednesday Book: A ride on Darwin's bandwagon

DARWIN'S SPECTRE: EVOLUTIONARY BIOLOGY IN THE MODERN WORLD

BY MICHAEL R ROSE,

PRINCETON UNIVERSITY PRESS, pounds 18.95

IN THE Twenties, the noted Harvard physiologist WJ Crozier warned his students against abandoning "proper" biological disciplines such as physiology and anatomy for the attractions of a "soft" subject such as evolution. "Evolution", he told them, "is a good topic for the Sunday supplements of newspapers, but it isn't science."

Seventy years on, few would dispute that evolutionary biology is now a "proper" science. As the great biologist Theodosius Dobzhansky put it, "Nothing in biology makes sense except in the light of evolution". In recent years many evolutionary biologists have tried to stretch Dobzhansky's axiom even further, claiming that not just in biology, but also in the social sciences, nothing makes sense except in evolution's light. The paradox, though, is that the more Darwinism seems to explain about human behaviour, the more that Darwinists write as if for Sunday supplements, abandoning scientific facts for speculative theories and flights of fancy.

This paradox is well expressed by Darwin's Spectre. Michael Rose, an expert on the biology of ageing, wants to reveal the universal importance of Darwinism. His book is divided into three sections. The first explores some of the key conceptual issues related to Darwinian theory (such as selection, adaptation and variation) while the second deals with applications of Darwinian theory (agriculture, medicine and eugenics). In both cases, the discussion is placed in a historical context. Rose provides, for instance, a potted biography of Darwin and a brief history of racial science.

You would be well advised to skip all this. The biology here will be familiar to anyone who has read authors such as Richard Dawkins, Steven Pinker and Randolph Nesse, while some of the history is distinctly dodgy. Any writer who admits that one of his key historical sources is Paul Johnson's The Birth of the Modern World does little to generate confidence.

The real interest of the book lies in the third section, in which Rose enters the debate about human nature. Rose wants to challenge traditional Darwinian explanations of human nature - such as evolutionary psychology - but from a Darwinian viewpoint. Evolutionary psychology holds that much of human behaviour has been shaped by natural selection, chosen because such behaviours helped our Stone Age ancestors the better to survive and reproduce.

Such a view, Rose observes, does not capture the key aspect of human behaviour - its "spectacular flexibility". Rose proposes a new theory, which he dubs "immanent Darwinism". All human behaviour, he argues, is implicitly Darwinist not because we have specific behaviours shaped by natural selection, but because human beings constantly calculate the best ways of passing on their genes. "On this model", he writes, "behaviour is determined by an immanent process of calculation taking place in the brain, not by genetic evolution arising from natural selection."

Rose accepts that "we don't experience our mental processes as having Darwinian ends". Rather, the Darwinian calculations that underlie our behaviour are subconscious. According to Rose, we all possess a "dynamic unconscious analogous to Freud's super-ego", except that it is driven by a "Darwinian calculus". The neural mechanism that calculates Darwinian odds, he suggests, is located in the brain's frontal lobes. "Our subjective experiences and calculations", Rose writes, "would be like dogs on a leash, the leash held by a Darwinian master of whom we are not normally aware."

This is all good fun, as Rose constantly jumps from one extravagant speculation to the next. The trouble is that speculation is rarely leavened by empirical facts. As Rose himself admits, "this type of theory patently invites incredulity" and is "such an extravagant hypothesis" that it makes evolutionary psychology "attractive by contrast". Rose's theory jettisons the best aspects of evolutionary psychology - its ability to explain some human traits, such as language - while retaining its more dubious aspects, including the tendency to wild speculation and the attempt to explain all human behaviour in terms of reproductive fitness.

Ultimately, Rose's vision of human nature derives not from science but from political ideology. The contrast between evolutionary psychology and immanent Darwinism corresponds, he believes, to the debate between Keynesianism and monetarism. Just like Keynesians, evolutionary psychologists have abandoned a libertarian view of human nature. According to evolutionary psychology "the behaviour of humans as producers, consumers, or intermediaries will be defined by specific behavioural mechanisms established by genetic adaptation".

With immanent Darwinism, however, "the economy becomes a kind of melee, barely held together by institutional frameworks, with congeries of Darwinian fiends struggling for advantage." Socialism, he adds, "would be compatible with the evolutionary psychology system", while with immanent Darwinism "there can be no peace for the social engineers". This is an argument that defies any kind of rational response. It's good Sunday-supplement stuff. But is it science?

The reviewer's book `The Meaning of Race' is published by Macmillan Press